35/11-4
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General information
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Wellbore history
GeneralWell 35/11-4 was designed to drill at a site located in block 35/11 which is situated on the eastern flank of the Viking Graben and northwest of the Horda Platform. The regional structural generally trends north-south, with some north-northeast components. Planned TD was 3317 m, which was prognosed to be near top Triassic. The primary objective for 35/11-4 was the Middle Jurassic Brent Group. Reservoirs were expected in the Tarbert, Ness, Etive and Oseberg formations. Secondary targets were possible sand development of Sognefjord Formation sand in the Late Jurassic as well as Paleocene sand mounds.Operations and resultsWildcat well 35/11-4 was spudded with the dynamically positioned semi-submersible installation Yatzy on 18 August 1990 and drilled to TD at 3127 m in the Early Jurassic Statfjord Formation. Yatzy was the first dynamically positioned drilling unit used offshore Norway and 35/11-4 was the rig's first well. This implied significant rig time spent on testing and down time due to failure of first-time equipment. At a depth of 2072 m one decided to sidetrack the well from 1700 m in order obtain cores from the hydrocarbon bearing zones of the Sognefjord formation. This led to a maximum deviation of 5.7 deg at 1765 m. The well was drilled with seawater and viscous pills down to 1009 m and with KCl/polymer mud from 1009 m to TD.The Lower Eocene consisted of a continuous argillaceous sequence and no reservoir rocks were penetrated. At 1647 m good reservoir quality sandstones were found in the Paleocene Lista Formation but they were not hydrocarbon bearing. Poor shows were observed in limestones of the Cretaceous Shetland Group. A total of four hydrocarbon-bearing zones were discovered in the Jurassic: in the Sognefjord Formation in the original hole and in the Sognefjord, Fensfjord Formations and Brent Group in the sidetrack hole. Mud log shows were recorded in most of the sandstone intervals from 1984 meters to the OWC in the Rannoch Formation at 2687 meters. The log evaluation indicated possible residual hydrocarbon from the OWC down to 2712 meters in the Oseberg Formation, mud logs indicated weak to poor shows over the same interval.Open hole logging, FMT pressure testing and FMT sampling proved movable hydrocarbons. The Upper Sognefjord Formation contained 11.4 meters of gas on top of 5.4 meters of oil with OWC at 2005 meters. The Lower Sognefjord Formation contained 14.6 meters of oil on water with OWC at 2050.5 meters. The Fensfjord contained 5.4 meters of oil in micaceous sandstones. FMT pressure data defined OWC in the Fensfjord at 2310 meters. Sandstones in the Brent Group contain 18.6 meters of gas on oil and 17.1 meters of oil on water. The GOC and OWC were found at 2670 and 2687 meters respectively.Reservoir quality of the sandstones is generally good though some are micaceous. In places the sandstones are very micaceous and the permeability is low. The micaceous zones may even act as barriers to the vertical migration of hydrocarbons particularly in the Sognefjord Formation. This may be one explanation for the separate hydrocarbon accumulations in the formation.Eight cores were cut in the Late and Middle Jurassic reservoirs; five in the Sognefjord Formation (108 m cut with 95% recovery) and three in the Fensfjord Formation (41.5 m cut with 98% recovery). FMT fluid samples were recovered from 1995 meters in the original hole (gas) and from 2000 m, 2038 m, 2290 m, and 2678 m in the sidetrack hole (all oil). A gas/condensate sample was recovered at 2634.5 m. A total of 125 sidewall cores were attempted and 100 were recovered.The well was suspended on 29 December 1990 as an oil and gas discovery.TestingDrill stem testing was planned for a re-entry in 1991. -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?YESCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]1010.003127.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11977.01981.4[m ]21982.02007.7[m ]32009.02027.8[m ]42033.02057.7[m ]52058.02083.8[m ]62285.02289.8[m ]72293.02300.4[m ]82303.02326.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]135.1Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Casing and leak–off tests
Casing and leak–off tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30505.036507.00.00LOTINTERM.201002.0261005.01.67LOTINTERM.13 3/81936.017 1/21940.01.88LOTINTERM.9 5/82798.012 1/42800.00.00LOTOPEN HOLE3127.08 1/23127.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]ACW17852035CBL VDL GR9061935COREGUN GR10132011COREGUN GR19603105COREGUN GR19972920DIFL AC GR10033129DIPOG GR19353129FMT HP GR16502011FMT HP GR19863095FMT HP GR19982634FMT HP GR20000FMT HP GR22900MLL DLL GR19353129MWD - GR RES DIR3543127SWAL GR12903130VELOCITY3723130ZDL CNL GR SL19353129ZDL GR10032043 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit372707734139713971448156116461710176018351835190019661966198421162284236526242624265626862707278527852825291830233082 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.49 -
Geochemical information
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Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf2.49pdf44.67 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured5051.04WATER BASED20.08.19905091.04WATER BASED21.08.19905091.04WATER BASED22.08.19905091.04WATER BASED23.08.199010091.04WATER BASED27.08.199010091.04WATER BASED27.08.199010091.04WATER BASED28.08.199010091.04WATER BASED29.08.199010091.04WATER BASED30.08.199010091.04WATER BASED31.08.199010091.04WATER BASED03.09.199010091.04WATER BASED05.09.199010091.04WATER BASED06.09.199010091.04WATER BASED07.09.199010091.04WATER BASED10.09.199010091.04WATER BASED10.09.199010091.04WATER BASED10.09.199010091.04WATER BASED11.09.199010091.04WATER BASED13.09.199010091.04WATER BASED14.09.199010091.04WATER BASED17.09.199010091.00WATER BASED18.09.199010091.00WATER BASED19.09.199010091.00WATER BASED20.09.199010091.00WATER BASED21.09.199010091.00WATER BASED24.09.199010091.00WATER BASED24.09.199010091.00WATER BASED24.09.199010091.00WATER BASED25.09.199010091.00WATER BASED27.09.199010091.00WATER BASED28.09.199010091.20WATER BASED01.10.199010091.02WATER BASED02.10.199010091.20WATER BASED03.10.199010091.20WATER BASED05.10.199010091.20WATER BASED08.10.199010091.04WATER BASED27.08.199010091.04WATER BASED04.09.199010091.00WATER BASED26.09.199010091.20WATER BASED02.10.199010091.20WATER BASED04.10.199010141.20WATER BASED08.10.199010361.20WATER BASED08.10.199010641.2022.024.0WATER BASED09.10.199011921.2119.027.0WATER BASED09.10.199011921.20WATER BASED15.10.199012651.20WATER BASED15.10.199012651.21WATER BASED15.10.199015701.2416.022.0WATER BASED16.10.199016601.2217.019.0WATER BASED17.10.199016921.2015.020.0WATER BASED29.10.199016931.22WATER BASED18.10.199017001.2315.020.0WATER BASED26.10.199017181.2015.020.0WATER BASED29.10.199017631.2114.020.0WATER BASED22.10.199017851.2015.020.0WATER BASED29.10.199018221.2115.021.0WATER BASED22.10.199018251.2115.020.0WATER BASED30.10.199019281.2115.020.0WATER BASED31.10.199019411.2115.020.0WATER BASED01.11.199019411.2115.020.0WATER BASED02.11.199019411.2115.020.0WATER BASED06.11.199019741.2115.020.0WATER BASED22.10.199019771.22150.0200.0WATER BASED06.11.199020001.2717.024.0WATER BASED30.11.199020031.10WATER BASED15.01.199220031.10WATER BASED16.01.199220031.10WATER BASED17.01.199220091.22150.0200.0WATER BASED06.11.199020301.22150.0200.0WATER BASED06.11.199020461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED06.01.199220461.10WATER BASED13.01.199220461.10WATER BASED13.01.199220461.10WATER BASED14.01.199220461.10WATER BASED06.01.199220461.10WATER BASED13.01.199220721.20150.020.0WATER BASED23.10.199020721.20150.020.0WATER BASED24.10.199020721.2015.020.0WATER BASED25.10.199020771.2418.024.0WATER BASED07.11.199020851.2418.024.0WATER BASED09.11.199020851.2418.024.0WATER BASED08.11.199021441.2017.026.0WATER BASED12.11.199022841.10WATER BASED12.12.199122841.10WATER BASED17.12.199122841.10WATER BASED17.12.199122841.10WATER BASED17.12.199122841.10WATER BASED17.12.199122841.10WATER BASED19.12.199122841.10WATER BASED19.12.199122841.10WATER BASED23.12.199122841.10WATER BASED23.12.199122841.10WATER BASED23.12.199122841.10WATER BASED24.12.199122841.10WATER BASED27.12.199122841.10WATER BASED27.12.199122841.10WATER BASED31.12.199122841.10WATER BASED31.12.199122841.10WATER BASED31.12.199122841.10WATER BASED17.12.199122841.10WATER BASED20.12.199122841.10WATER BASED27.12.199122851.2116.024.0WATER BASED13.11.199022901.2216.024.0WATER BASED13.11.199023011.2415.022.0WATER BASED15.11.199023851.2417.026.0WATER BASED16.11.199025251.2716.027.0WATER BASED19.11.199026291.2717.024.0WATER BASED27.11.199026291.2717.024.0WATER BASED28.11.199026291.2717.024.0WATER BASED29.11.199026291.2717.024.0WATER BASED19.11.199026291.2717.024.0WATER BASED27.11.199026511.2717.024.0WATER BASED30.11.199026641.2717.024.0WATER BASED03.12.199026831.10WATER BASED05.12.199126831.10WATER BASED09.12.199126831.10WATER BASED09.12.199126831.10WATER BASED10.12.199126831.10WATER BASED06.12.199126831.10WATER BASED09.12.199126981.2717.024.0WATER BASED03.12.199028101.2615.020.0WATER BASED27.12.199028101.2615.020.0WATER BASED27.12.199028101.2615.020.0WATER BASED31.12.199028101.2615.020.0WATER BASED31.12.199028101.2615.020.0WATER BASED31.12.199028101.2615.020.0WATER BASED02.01.199128101.2615.020.0WATER BASED02.01.199128101.2615.020.0WATER BASED07.01.199128101.2615.020.0WATER BASED07.01.199128101.2615.020.0WATER BASED08.01.199128101.2615.020.0WATER BASED08.01.199128101.2615.020.0WATER BASED08.01.199128101.2615.020.0WATER BASED14.01.199128101.2615.020.0WATER BASED14.01.199128101.2615.020.0WATER BASED14.01.199128101.2615.020.0WATER BASED31.12.199028101.2615.020.0WATER BASED07.01.199128221.2817.024.0WATER BASED04.12.199028741.2615.020.0WATER BASED04.12.199029101.2615.020.0WATER BASED05.12.199029101.2615.020.0WATER BASED11.12.199029101.2615.020.0WATER BASED12.12.199029101.2615.020.0WATER BASED14.12.199029101.2615.020.0WATER BASED14.12.199029101.2615.020.0WATER BASED19.12.199030291.2615.020.0WATER BASED19.12.199030291.2615.020.0WATER BASED19.12.199031271.2615.020.0WATER BASED27.12.199031271.2615.020.0WATER BASED19.12.199031271.2615.020.0WATER BASED27.12.199031271.2615.020.0WATER BASED27.12.199031271.2615.020.0WATER BASED27.12.199031271.2615.020.0WATER BASED27.12.199031271.2615.020.0WATER BASED27.12.1990 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1020.0[m]DCRRI1050.0[m]DCRRI1090.0[m]DCRRI1130.0[m]DCRRI1210.0[m]DCRRI1250.0[m]DCRRI1300.0[m]DCRRI1360.0[m]DCRRI1410.0[m]DCRRI1430.0[m]DCRRI1450.0[m]DCRRI1470.0[m]DCRRI1510.0[m]DCRRI1530.0[m]DCRRI1580.0[m]DCRRI1670.0[m]DCRRI1710.0[m]DCRRI1758.0[m]SWCRRI1790.0[m]SWCRRI1810.0[m]DCRRI1855.0[m]DCRRI1880.0[m]DCRRI1903.0[m]DCRRI1957.0[m]SWCRRI1968.0[m]SWCRRI1970.0[m]DCRRI1975.0[m]DCRRI1980.0[m]CRRI1981.0[m]CRRI1988.0[m]CRRI1990.0[m]SWCRRI2001.0[m]CRRI2003.0[m]SWCRRI2011.0[m]CRRI2014.0[m]CRRI2025.0[m]CRRI2031.0[m]CRRI2036.0[m]CRRI2040.0[m]CRRI2044.0[m]CRRI2067.0[m]CRRI2275.0[m]DCRRI2280.0[m]DCRRI2285.0[m]DCRRI2286.0[m]CRRI2291.0[m]CRRI2295.0[m]CRRI2295.0[m]DCRRI2300.0[m]CRRI2304.0[m]CRRI2307.0[m]CRRI2314.0[m]CRRI2326.0[m]CRRI2530.0[m]DCRRI2540.0[m]DCRRI2545.0[m]DCRRI2610.0[m]DCRRI2620.0[m]DCRRI2790.0[m]DCRRI2865.0[m]DCRRI2875.0[m]DCRRI2925.0[m]DCRRI3120.0[m]DCRRI